JP2005188505A - Gas turbine part with protective film, and method of forming protective film on super alloy metal substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide parts of a gas turbine provided with a protective film, and to provide a method of forming the protective film on a super alloy metal substrate. <P>SOLUTION: A part of a gas turbine comprises the super alloy metal substrate, a bonding lower layer formed on the substrate and comprising an intermetallic compound of aluminum, nickel and platinum, and a ceramic outer layer fixed to an aluminum layer formed on the bonding lower layer. The bonding lower layer essentially contains a Ni-Pt-Al three-component system structured of an aluminum enriched α-NiPt type structure, especially a Ni-Pt-Al three-component system having a composition Ni<SB>z</SB>Pt<SB>y</SB>Al<SB>x</SB>(z, y and x respectively satisfies expressions 0.05 ≤ z ≤ 0.40, 0.30 ≤ y ≤ 0.60 and 0.15 ≤ x ≤ 0.40). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to producing a protective coating on a superalloy metal substrate.

  In the field of application of the present invention, parts that can maintain mechanical strength at high temperatures, especially gas turbine parts such as turbine blades of turbojet aircraft, are made.

  In order to increase performance, particularly efficiency, it is desirable to operate the gas turbine at the highest possible temperature. It is common practice to use superalloys to make hot part components. These alloys typically contain nickel as a major component and additional elements selected from chromium, cobalt, aluminum, molybdenum, titanium, tantalum, and many other elements.

  The operating temperature can be increased by providing a protective coating on the metal substrate of such a component that forms a thermal barrier.

  It is known to produce a protective coating comprising a ceramic outer layer and a metal underlayer, in particular a bond underlayer comprising at least one other metal such as aluminum and platinum.

The junction underlayer inserted between the superalloy metal substrate and the ceramic outer layer performs the following functions:
Forming an alumina film on the surface and allowing it to survive, thereby increasing the bond with the ceramic outer layer;
Protecting the substrate from corrosion due to oxidation by oxygen in the surrounding medium that somehow passes through the outer ceramic layer; and
If nothing is done, it will contaminate the alumina film and consequently affect the interface between the bonding lower layer and the outer ceramic layer, and thus constitute a diffusion barrier for certain elements of the metal substrate that affect its adhesion .

  The inclusion of reactive elements such as yttrium, cerium, hafnium, or lanthanide in the junction underlayer reinforces its diffusion barrier function and increases the durability of the “adhesive” film of alumina.

  It is well known that an MCrAlY type (M is a metal such as Fe, Ni, Co) is formed by a method such as plasma radiation without inducing a reaction with the substrate. Adhesion to the substrate is mechanical. See, for example, U.S. Pat. Nos. 4,055,704 and 5,824,423. Nevertheless, in order to obtain a thermally stable lower layer, the lower layer needs to be relatively thick. Generally, at least the thickness is in the range of 50 micrometers (μm) to 100 μm, and such thickness is disadvantageous in terms of weight.

  Another known method consists in making the junction underlayer from an intermetallic compound that can be made thinner for thermal stability. Intermetallic compounds containing aluminum and platinum have been found to have good properties.

  Thus, the methods described in US Pat. Nos. 5,716,720 and 5,856,027 have electroplated a platinum layer on a substrate made of a nickel-based superalloy, followed by 1000 The purpose is to perform aluminum deposition at a temperature exceeding ℃. Nickel generated from the substrate diffuses into the bonding lower layer. Before forming the ceramic outer layer of yttria-stabilized zirconia obtained by physical vapor deposition (PVD), for example, an alumina film is formed on the surface of the bonding lower layer by heat treatment. Reactive elements can be introduced into the junction underlayer during the aluminum deposition stage. In its outer part above the diffusion layer around the substrate, the bonding underlayer shows an intermediate phase comprising 18-28 wt.% Aluminum, 50-60 wt.% Nickel, and 8-35 wt. This corresponds to the β-type solid solution phase of the aluminum two-phase diagram (β-NiAl).

  Another method described in US Pat. No. 5,238,752 is to form a bonding underlayer made of an intermetallic compound, particularly a compound of aluminum and platinum, on a superalloy substrate. The junction underlayer is made by pack cementation at a temperature above 985 ° C. to a thickness above 25 μm. For example, before forming the ceramic outer layer of yttria-stabilized zirconia by physical vapor deposition, an alumina film is formed by oxidation of the surface of the bonding lower layer.

  European patent application EP 0,985,744 describes the formation of a platinum layer by electroplating or chemical vapor deposition on a nickel-based superalloy substrate and aluminum diffused into the platinum layer made of gaseous halide. Yet another method is described that includes depositing a layer. Sulfur is removed after each deposition by heat treatment at temperatures above 1050 ° C. along with surface rust removal so as to remove sulfur that is detrimental to the adhesion of the resulting alumina film to the surface of the resulting bonded underlayer. Is done.

  US Patent Application No. 2002/0037220 is formed by alternately physical depositing a plurality of individual layers of aluminum and metals from the platinum group and by an exothermic reaction between the metals of the layers formed. Disclosed method. By using physical vapor deposition, the temperature of the substrate is relatively low, and the elements of the substrate remain at a value well below the temperature at which the element tends to diffuse into the deposit formed from that temperature.

  It is an object of the present invention to provide a protective coating between a substrate and a ceramic outer layer that has a bonding underlayer that is stable and exhibits a long-term resistance to delamination of the ceramic layer but is thin and thus light in weight A gas turbine component comprising a superalloy metal substrate comprising:

  The object is to provide a superalloy metal substrate, a bonding lower layer formed on the substrate and containing an intermetallic compound including aluminum, nickel and platinum, and a ceramic outer shell fixed to an alumina film formed on the bonding lower layer. And the bonding underlayer is achieved in accordance with the present invention by a gas turbine component that essentially comprises a Ni-Pt-Al ternary system comprised of an aluminum enriched α-NiPt type structure.

  A feature of the present invention is that at least most of the bonding lower layer is constituted by an α-type solid solution phase of nickel (Ni) and platinum (Pt) two-phase diagrams, and also incorporates aluminum (Al).

  This is because even if it is thin, the phase stability is high so that the bonding lower layer can be produced without affecting the properties of the thermal protection material, particularly the robustness. The thermal protection material shows increased resistance to delamination even after repeated thermal cycles.

  In addition, if the substrate is made of a nickel-based superalloy, the diffusion of nickel from the substrate to the bonding layer can change the composition of the bonding layer, although it may change the composition of the bonding layer, over time. There is no sex. Therefore, there is no possibility of changing the stability of the α-NiPt intermetallic compound, so that the closer the initial nickel content is to the minimum value of the α-NiPt region, the more significant this is.

The α-type NiPt solid phase enriched with Al is known per se, and in particular, Janice L. et al. Scripta Metallurgica et Materiala, Vol., Entitled “Phase stability in (Ni, Pt) ₃ Allloys” by Kann et al. 31, no. 11, pp. It can be characterized by its crystal structure as described in a paper published in 1461-1464, 1994.

  Reference text for such phases is given in B. Entitled "Effects on platinum on the interdiffusion and oxidation behavior of Ni-Al-based alloys" by Gleeson et al., The Proceedings of the 6th International Symposium on High Temperature Corrosion and Protection of Materials, Materials Science Forum, Vols. 461-464, pp. It can also be found in a paper published in 213-222, 2004.

Conveniently, the Ni—Pt—Al ternary system has a composition of Ni _z Pt _y Al _x , where z , y , and x are 0.05 ≦ z ≦ 0.40. 0.30 ≦ y ≦ 0.60 and 0.15 ≦ x ≦ 0.40.

  In addition to Al, Ni, and Pt, the junction underlayer is selected from one or more additional metals, particularly at least one metal selected from chromium and cobalt that contributes to stability, and / or palladium, ruthenium, and rhenium. At least one noble metal.

  The junction underlayer can also include at least one reactive element selected from the group consisting of yttrium, zirconium, hafnium, and lanthanides.

  In any case, it is preferred that the majority of the junction underlayer remain formed by the Ni—Pt—Al ternary system, which exhibits at least 75% (atomic percentage) of the underlying composition.

  The thickness of the bonding lower layer is conveniently in the range of 2 μm to 120 μm, preferably less than 40 μm. A thickness of less than 40 μm can be selected for stability given by the presence of the α-NiPt phase, thereby limiting the fabrication cost and mass of the junction underlayer.

  Another object of the present invention is to provide a method for forming a thermal protection coating on a superalloy metal substrate with a bonded underlayer that is stable and can reduce mass.

  This object is achieved by a method comprising forming a bonding underlayer on a substrate, wherein the lower layer contains an intermetallic compound of aluminum, nickel and platinum, and is fixed to an alumina film in the bonding lower layer. Is forming. In that method, according to the present invention, a junction underlayer is formed that essentially comprises a Ni—Pt—Al ternary system constituted by an aluminum enriched α-NiPt type structure.

  In one embodiment of the method, the junction underlayer is made by forming a coating on the substrate with a composition corresponding to the composition desired for the underlayer. In that case, an overlay method is used, that is, a film-forming method that does not substantially or significantly contain diffusion of elements from the substrate into the film.

  Among suitable methods, mention may be made of physical vapor deposition, deposition by cathodic sputtering or plasma radiation, and electrodeposition.

  Accordingly, a bonding underlayer can be formed by physical vapor deposition of at least a plurality of individual layers of platinum, nickel, and aluminum, and by reacting the deposited layers with each other.

  It is also possible to deposit at least some layers comprising a plurality of components of the bonding underlayer in a pre-alloyed form. For example, prealloyed layers such as NiPt or PtAl can be alternately deposited with layers of Al or Ni.

  It is also possible to envisage forming the bonding underlayer by physical vapor deposition from a source having a composition corresponding to the composition desired for the bonding underlayer, for example by plasma radiation from a mixture of prealloyed powders. .

  In another embodiment of the invention, the bonding underlayer is at a moderate temperature, i.e. less than 900 ° C., by physical vapor depositing at least a plurality of alternating individual layers of platinum and aluminum on a nickel-based superalloy substrate. Formed by exothermic reaction of the metal from those deposited layers, generally at a temperature of about 700 ° C., and by heat treatment to diffuse the nickel from the substrate into the bonding underlayer. The heat treatment can be performed separately from forming the ceramic outer layer. Alternatively, it may be the result that when the heat treatment is performed at a relatively high temperature, the heat treatment forms a ceramic outer layer. If the lower layer is relatively thin, i.e. less than 10 μm, then a heat treatment at a temperature of 900 ° C. or higher is sufficient to cause diffusion of nickel from the substrate to the entire bonded lower layer, so that the thickness is It has been found by the applicant that a thicker will probably require a higher temperature. It has also been found that such diffusion results in an α-NiPt type stable phase.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood by reading the following description given by way of non-limiting representation.

Reference is made to the accompanying drawings. inside that,
FIG. 1 is a very schematic cross-sectional view of a superalloy metal substrate with a protective coating.

  FIG. 2 is a diagram of unit cell characteristics of the aluminum-enriched α-NiPt solid solution phase.

  FIG. 3 is a schematic diagram illustrating one embodiment of the method of the present invention.

  4-6 are schematic diagrams illustrating an example of the first stage in the method of FIG.

  FIG. 7 is a schematic diagram illustrating another embodiment of the method of the present invention.

  FIG. 8 is a photograph showing a cross-sectional view of a protective coating taken on a superalloy metal substrate in accordance with one embodiment of the present invention, taken with a scanning electron microscope.

  FIG. 9 is a chart showing the results of tests conducted on parts made with the coating of the present invention and parts made according to the prior art.

  10 and 11 are photographs showing a cross-section of a protective coating taken using a scanning electron microscope before and after moderate heat treatment and produced using another embodiment of the present invention.

  The following description relates to producing protective coatings on superalloy metal parts, and generally on gas turbine parts such as turbojet turbine blades.

  The protective coating is of the type shown very schematically in FIG. On a metal substrate 10 made of a superalloy, it is fixed to a bonding lower layer 12 made of an intermetallic compound mainly composed of aluminum, nickel, and platinum, and an alumina film 14 formed on the surface of the bonding lower layer. A coating including the outer ceramic layer 16 is formed.

According to the present invention, most of the intermetallic compounds forming the bonding lower layer include a Ni-Pt-Al ternary system enriched with aluminum composed of α-NiPt type phases. Such a phase can be defined by its lattice structure, as shown in FIG. This structure is an L1 _o type face-centered tetragonal system. Ni and Al atoms are located at the apex and center of the (001) plane, while Pt atoms are located at the centers of the (100) and (010) planes. For one unit cell, dimensions a 1 , b 2, and c (FIG. 2) are about 0.37 nm ≦ a = b ≦ 0.40 nm and 0.35 nm ≦ c ≦ 0.36 nm. z, y, and x is, _Ni z _Pt y Al _x ternary is 0.05 ≦ z ≦ 0.40,0.30 ≦ y ≦ 0.60, and more 0.15 ≦ x ≦ 0.40 Is preferably selected.

  B. As confirmed by the above article by Gleeson et al., The region containing the α-NiPt phase is completely separate from the region containing the β-NiAl phase.

  The bonding underlayer composition helps to reinforce the diffusion barrier function for elements other than Ni, Al, and Pt, especially certain elements of the substrate that may be detrimental to the strength of the protective coating. Reactive elements selected from yttrium, zirconium, hafnium, and lanthanides that enhance persistence can be added. It is also possible to add other metals having a beneficial effect, for example palladium, ruthenium or rhenium, or even cobalt and / or chromium, which improve the thermal stability of the coating.

  The alumina film 14 is formed by oxidation of aluminum as a diffusion barrier. It provides a protective function against corrosion due to oxidation. It also attaches the ceramic outer layer 16 due to its “adhesion” properties.

  The ceramic jacket 16 essentially provides a thermal insulation function. The coating is made of a refractory oxide such as zirconia, yttrium oxide, or yttria stabilized zirconia. The coating can be formed by physical vapor deposition, for example, by electron beam vapor deposition, or by plasma based vapor deposition, as is well known in the art.

The composition of the junction underlayer may be as follows (in percent of atoms):
Ni-Pt-AI ternary system as defined above in the range of 75% to 100%,
Cobalt and / or chromium in the range of 0% to 10%,
The reactive element (s) selected from Y, Zr, Hf and lanthanides in the range of 0% to 5%, and
A noble metal selected from Pd, Ru, and Rh in the range of 0-10%.

  The thickness of the bonding lower layer is preferably in the range of 2 μm to 120 μm. Due to the high thermal stability afforded by the α-NiPt phase, it may be advantageous for this thickness to be less than 40 μm, or even less than 20 μm.

First Embodiment In the first embodiment (FIG. 3), the junction underlayer does not cause substantial or significant diffusion of elements from the substrate by creating a film having a desired composition in the junction underlayer, That is, it is formed by performing an overlay type method (step 20).

  Thereafter (step 22), the outer layer is formed in the bonding lower layer with the growth of the alumina film formed on the surface thereof. For this purpose, it is possible to use physical vapor deposition under an electron beam (EB-PVD). The metal substrate carrying the bonding underlayer is placed in a sealed box over a ceramic source, eg, a yttria stabilized zirconia target. Deposition is performed by exciting an electron gun facing the ceramic source under a reduced pressure atmosphere containing a mixture of argon and oxygen. The method is well known in the art.

  Stage 20 can be performed in several ways, particularly under an arc, with or without assistance from the plasma, by performing physical vapor deposition methods such as cathode sputtering, electron beam PVD, or vapor deposition.

  In the first modified embodiment (FIG. 4), stage 20 consists of M times for each series of single layer depositions of platinum (stage 201), aluminum (stage 202), platinum (stage 203), and nickel (stage 204). Repeat and then include the final deposition of the platinum monolayer (step 205). Next, before forming the ceramic outer layer, a moderate heat treatment (step 206) can be performed to form an intermetallic compound by causing a reaction between the single layer metals. The heat treatment is performed at a temperature lower than 900 ° C., for example, about 700 ° C. Therefore, the diffusion of elements from the substrate to the adjacent portion of the intermetallic compound is not promoted. The heat treatment is performed, for example, in a vacuum or inert atmosphere for a duration in the range of 0.5 hours (h) to 3 hours.

  It should also be appreciated that moderate heat treatment is optional and that intermetallic compounds may also form under the influence of temperature increases that occur during the creation of the ceramic outer layer.

  In the procedure of depositing a monolayer, it is preferable to place a monolayer of aluminum between two monolayers of platinum to avoid any reaction between aluminum and nickel that may interfere with the diffusion of the intermetallic platinum. I have to admit that. The first monolayer is essentially a layer composed of platinum because platinum is unlikely to diffuse much into the substrate. The last monolayer is also preferably a platinum layer since platinum is less likely to oxidize in air or oxygen partial pressure at the end of fabrication of the bonding underlayer.

  The monolayer is made to have an individual thickness of less than 2000 nanometers (nm), preferably only 1500 nm, at least for aluminum. The layer thickness may be chosen to be well below this threshold, for example only 200 nm. If it is desired to obtain a structure that is homogeneous after heat treatment, i.e. that does not leave any trace that the bonding underlayer is formed from superposed layers, such a relatively thin thickness is selected.

  The number of consecutive M is determined as a function of the desired monolayer thickness and total thickness for the junction underlayer. Depending on the value of the total thickness, the number of single layers may vary in the range from several to tens or hundreds.

  It should be appreciated that the deposited monolayer may be of different thickness.

  In all cases, the ratio between the total layer thicknesses for each metal is a function of the desired composition for the intermetallic compound that forms the bonded underlayer.

  In a second modified embodiment (FIG. 5), step 20 comprises a binary series of single layer depositions, such as NiPt (), prior to any moderate heat treatment (step 206) as in the method of FIG. Stage 210), and N iterations of aluminum (stage 211). Of course, in a modified embodiment, it is possible to alternate the deposition of the PtAl binary system and nickel Ni. The composition of the NiPt binary system, the monolayer thickness, and the number thereof are selected as a function of the desired composition and thickness for the junction underlayer.

  In a third modified embodiment (FIG. 6), stage 20 includes a Ni-Pt-Al ternary P layer (stage 215) prior to any modest heat treatment (stage 206). Contains.

  Each layer is given a composition that corresponds to the desired composition for the bonded underlayer.

  As described above, in the method of FIGS. 4-6, especially when using the PVD method, it is made of nickel, platinum, or aluminum, or made of two alloys of those materials, or all three. Made of metal alloys, these metals use sources or targets that exist, for example, in powder form. Also, when additional metals or other elements are to be incorporated into the junction underlayer, they can be supplied by additional sources or targets to be deposited in a separate monolayer. Alternatively, they can be prealloyed at one or more desired ratios of nickel and / or platinum and / or aluminum sources or targets.

  In yet another modified embodiment, the bonding underlayer can be formed by electrodeposition without significant interaction with the substrate. It can be continued by depositing successive layers of different metals or by co-deposition of these metals.

Second Embodiment In the second embodiment (FIG. 7), because the metal substrate is made of a nickel-based superalloy, the junction underlayer is essentially aluminum in the first part of the method. In the subsequent part of the method, by forming an intermetallic compound comprising platinum and platinum, the nickel from the substrate is diffused by increasing the temperature before or during the formation of the ceramic outer layer.

  The first part of the method uses physical vapor deposition to alter the exothermic reaction between alternating layers of platinum (stage 30) and aluminum (stage 32) and between the layers formed thereby. Can be done by waking up. To this end, the method described in the above-mentioned US patent application 2002/0037220 can be used.

  For reasons already indicated, the first monolayer to be deposited on the substrate and the last monolayer to be deposited (stage 34) are preferably platinum layers.

  A moderate heat treatment step 36 is performed to form an intermetallic compound by an exothermic reaction between the formed single layer platinum and aluminum. The heat treatment is performed at a temperature lower than 900 ° C., for example, about 700 ° C. Therefore, the diffusion of the element from the metal substrate to the adjacent portion of the intermetallic compound is not promoted. The heat treatment is performed under a non-oxidizing atmosphere, for example, under a vacuum or inert atmosphere for a duration ranging from 0.5 hours to 3 hours, for example, about 2 hours. During heat treatment, aluminum in any layer diffuses into the adjacent platinum layer. A thin film of alumina forms on the surface of the bonding underlayer thus obtained during subsequent exposure to the oxidizing medium.

  The monolayer is made to have an individual thickness of at least less than 2000 nm, preferably only 1500 nm, at least for aluminum. It is possible to choose this thickness to be well below this threshold, for example only 200 nm.

  The thickness and number of layers are selected to obtain an Al / Pt ratio corresponding to the desired Al / Pt ratio in the junction underlayer and to obtain the desired thickness therefor.

  Single layers of platinum and aluminum can be deposited by cathodic sputtering, by electron beam physical vapor deposition, or by vapor deposition under an arc with or without plasma. The method makes it possible to adjust the amount of deposited metal and thus the thickness of the monolayer quite precisely. Such methods are well known per se and use sources or targets made of platinum and aluminum.

  By using at least one additional metal and / or at least one reactive element by using one or more additional sources or targets, or by incorporating those materials into platinum and aluminum sources or targets, It can be deposited in the junction underlayer.

  Thereafter, the ceramic outer layer is fabricated (step 37) after raising the temperature of the substrate to a value high enough to diffuse the nickel contained in the metal substrate into the bonding underlayer. This temperature should be chosen to be higher and higher to increase the thickness of the junction underlayer. The temperature is preferably equal to or greater than 900 ° C. so that the thickness is in the range of 2 μm to 10 μm, and may exceed 1000 ° C. to increase the thickness.

  Other metals from the substrate such as cobalt and chromium are likely to diffuse. Nevertheless, the junction underlayer is contained in the substrate, such as tungsten, molybdenum, tantalum, etc., which can have a detrimental effect on the strength of the protective coating, especially the sustainability of the alumina film on the surface of the junction underlayer. Maintains its diffusion barrier function against potential elements.

  The present applicant was able to show that nickel diffusing into the bonding lower layer forms an α-NiPt type stable phase in cooperation with platinum.

  In a modified embodiment, a heat treatment at a temperature of at least 900 ° C. can be performed prior to forming the ceramic outer layer in an attempt to diffuse nickel from the substrate into the bonding lower layer.

  Made of nickel-based single crystal superalloy with the following composition (weight percent): 6.5% Co, 7.5% Cr, 5.3% Al, 1.2% Ti, A metal part with 8% Ta, 2% Mo, 5.5% W and the balance Ni was used.

  Applying the second embodiment (FIG. 7), platinum and aluminum layers were alternately attached to the parts by cathode vapor deposition and physical vapor deposition. 84 platinum monolayers, each having a thickness of 30 nm, were alternately deposited with 83 aluminum monolayers, each having a thickness of 66 nm.

In order to cause an exothermic reaction between the single layers, the temperature was raised to 700 ° C. for 2 hours to form a PtAl ₂ type platinum-aluminum intermetallic compound in a layer having a thickness of 7.5 μm.

A zirconia ZrO ₂ ceramic outer layer (representing 8 wt%) stabilized with yttrium oxide Y ₂ O ₃ was then deposited. Deposition was performed by electron beam physical vapor deposition as described above. The temperature of the substrate was raised to about 1000 ° C. and the duration was selected so that an outer layer of yttria stabilized zirconia having a thickness equal to about 125 μm was formed.

The procedure was the same as in Example 1, but the number of platinum and aluminum monolayers was changed to PtAl ₂ type intermetallic compound in a layer having a thickness equal to about 2.5 μm after an exothermic reaction between them. It was restricted to obtain.

  The micrograph of FIG. 8 shows the results obtained.

(For comparison)
The bonding lower layer corresponding to the β-type phase enriched with platinum in the Ni—Al two-phase diagram by a method known in the prior art on a substrate having the same composition as the substrates of Examples 1 and 2. Was formed by electrodeposition of a platinum layer and by aluminum deposition. The thickness of the bonding lower layer was 60 μm. A ceramic outer layer was then formed as described in Example 1.

  The ability to withstand thermal cycling in the oxidizing medium (air) was tested on parts A, B, and C obtained in Examples 1, 2, and 3, respectively. In each cycle, the temperature was rapidly raised to 1100 ° C. and maintained there for 1 hour, then returned to ambient temperature and maintained there for 15 minutes.

  As shown in FIG. 9, the component B sufficiently endured 624 cycles. It is a very noteworthy result considering that it is a very thin (2.5 μm) junction underlayer compared to the currently used junction underlayer thickness (most commonly 60 μm). . Parts A and C fully survived 1086 cycles.

  The ability to use a thin bonded underlayer results in reduced fabrication time, reduced material costs (even if the platinum content is relatively high), and reduced weight, all of which are important advantages.

  The single crystal superalloy metal part specified in Example 1 was attached with a layer by repeating the arrangement of Pt, Al, Pt, Ni together with the last Pt layer (the first as shown in FIG. 4). Modified embodiment of the embodiment). A physical vapor deposition method by cathode sputtering was used. Deposit 13 individual Pt monolayers each having a thickness of 181 nm, 6 individual layers of Ni each having a thickness of about 268 nm, and 6 individual layers of Al each having a thickness of about 171 nm I let you.

  In order to cause a reaction between the single layers without moving from the substrate of the single crystal superalloy, an appropriate heat treatment was performed at a temperature of about 700 ° C. under vacuum. Thus, a coating made of an intermetallic compound having a thickness approximately equal to 7.1 μm was obtained. The composition in atomic percentage of the coating was 45% Pt, 28% Al, and 27% Ni. The coating was examined by X-ray diffraction and as a result showed the presence of the crystal structure characteristics of the aluminum enriched α-NiPt phase.

  10 and 11 each show the coating in cross-section before and after moderate heat treatment.

FIG. 3 is a very schematic cross-sectional view of a superalloy metal substrate with a protective coating. It is a figure of the unit cell characteristic of aluminum concentration alpha-NiPt solid solution phase. 1 is a schematic diagram illustrating one embodiment of the method of the present invention. Fig. 4 is a schematic diagram showing an example of the first stage in the method of Fig. 3; Fig. 4 is a schematic diagram showing an example of the first stage in the method of Fig. 3; Fig. 4 is a schematic diagram showing an example of the first stage in the method of Fig. 3; 2 is a schematic diagram illustrating another embodiment of the method of the present invention. It is a photograph which shows the cross-sectional view of the protective film which image | photographed with the scanning electron microscope and produced on the superalloy metal substrate according to one Embodiment of this invention. It is a table | surface which shows the result of the test done about the components produced with the film of this invention, and the components produced according to the prior art. It is a photograph which shows the cross section of the protective film which image | photographed with the scanning electron microscope before and after moderate heat processing, and produced using other embodiment of this invention. It is a photograph which shows the cross section of the protective film which image | photographed with the scanning electron microscope before and after moderate heat processing, and produced using other embodiment of this invention.

Explanation of symbols

10 Metal substrate 12 Bonding lower layer 14 Alumina film 16 Ceramic outer layer

Claims (19)

  A superalloy metal substrate characterized by comprising a Ni-Pt-Al ternary system essentially composed of an aluminum-enriched α-NiPt type structure, and an aluminum, nickel layer formed on the substrate. And a joining lower layer containing an intermetallic compound containing platinum, and a ceramic outer shell fixed on an alumina film formed on the joining lower layer. In the Ni—Pt—Al ternary system, z , y , and x are 0.05 ≦ z ≦ 0.40, 0.30 ≦ y ≦ 0.60, and 0.15 ≦ x ≦ 0.40. The gas turbine component according to claim 1, comprising the composition Ni _z Pt _y Al _x .   The gas turbine component according to claim 1, wherein the bonding lower layer further includes at least one additional metal other than aluminum, nickel, and platinum.   The gas turbine component according to claim 3, wherein the bonding lower layer further includes at least one metal selected from cobalt and chromium.   The gas turbine component according to claim 3, wherein the bonding lower layer includes a metal selected from palladium, ruthenium, and rhenium.   The said joining lower layer further contains at least 1 reactive element selected from the group comprised by a yttrium, a zirconium, hafnium, and a lanthanide, The Claim 1 characterized by the above-mentioned. Gas turbine parts.   7. The gas turbine component according to claim 1, wherein a thickness of the bonding lower layer is in a range of 2 μm to 120 μm.   The gas turbine component according to claim 7, wherein a thickness of the bonding lower layer is less than 40 μm.   The gas turbine component according to claim 7, wherein a thickness of the bonding lower layer is less than 20 μm.   A junction underlayer comprising an intermetallic compound of aluminum, nickel, and platinum, characterized in that a junction underlayer essentially comprising a Ni-Pt-Al ternary system composed of an aluminum-enriched α-NiPt structure is formed Forming a thermal protective coating on the superalloy metal substrate, comprising forming a ceramic outer layer secured to an alumina film overlying the bonding layer.   The method according to claim 10, wherein the bonding lower layer is formed by forming a film having a composition corresponding to a desired composition for the lower layer on the substrate.   The method according to claim 11, wherein the bonding lower layer is formed by forming a film by physical vapor deposition.   13. The method of claim 12, wherein the bonding underlayer is formed by physical vapor deposition of at least a plurality of single layers of platinum, nickel, and aluminum, respectively, and by reacting the metals of the vapor deposition layer with each other.   The method of claim 12, wherein the bonding lower layer is formed by depositing each layer, and at least a portion of each layer includes a plurality of lower layer components in a pre-alloyed form.   The method of claim 12, wherein the bonding underlayer is formed by depositing a pre-alloyed composition corresponding to a desired composition for the underlayer.   The method according to claim 11, wherein the bonding lower layer is formed by forming a film by electrodeposition.   To physically vapor-deposit at least a plurality of alternating monolayers of platinum and aluminum on a nickel-based superalloy substrate, to cause an exothermic reaction between the deposited layer metals, and to diffuse nickel from the substrate to the bonding underlayer, The method according to claim 10, wherein the bonding lower layer is formed by heat treatment at a temperature of 900 ° C. or more.   The method according to claim 16, wherein the heat treatment is performed at a temperature of 900 ° C. or more while forming the ceramic outer layer.   The method according to claim 16, wherein the heat treatment is performed at a temperature of 900 ° C. or more before forming the ceramic outer layer.

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